1. Field of the Invention
With the advancement of personal computers, particularly, the advancement of portable personal computers in recent years, the demand for liquid crystal display, particularly, color liquid crystal display tends to increase. It is however necessary to reduce the cost of the color liquid crystal display devices for further spreading them. There is an increasing demand for reduction in the cost of color filter substrates particularly given much weight from the viewpoint of the cost.
2. Related Background Art
As a process for producing a color filter substrate at low cost, it has been proposed to first form light-screening black matrices on a glass substrate and separately applying inks to space areas between the black matrices by an ink-jet system to form a color filter. With respect to this process, in order to successfully fill the inks in the space areas between the black matrices, which correspond to respective pixels, a material hard to wet with the inks and easy to repel the inks are investigated as a material for the black matrices.
For example, Japanese Patent Application Laid-Open No. 7-35917 has proposed a process in which black matrices are formed with a material having a contact angle with inks of at least 20.degree., and the inks are applied to space areas between the black matrices. In Japanese Patent Application Laid-Open No. 7-35915, it has also been proposed to use a material having a contact angle with water of at least 40.degree. as a material for black matrices. In Japanese Patent Application Laid-Open No. 6-347637, it has been proposed to select materials for a substrate, inks and black matrices, the critical surface tensions of which shall be lined up in the order of "the substrate surface&gt;the inks&gt;the black matrix surface", and be preset in such a manner that that of the black matrix surface is lower than 35 dyn/cm, that of the substrate surface is not lower than 36 dyn/cm, and the inks have a difference in the critical surface tension by at least 5 dyn/cm from both substrate surface and black matrix surface. In all these proposals, it has been proposed to contain a fluorine compound or a silicon compound in materials for the black matrices to impart a high ink repellency to the materials.
Besides, in Japanese Patent Application Laid-Open No. 4-121702, it has been proposed to form banks having a hydrophilicity opposite to a substrate and to pour inks in spaces between the banks. However, detailed description as to materials is not made.
By imparting the ink repellency to the black matrices like these examples, it is possible to repel any inks flown off on the black matrices back to the space areas between the black matrices. Therefore, the problem that the inks are not successfully filled in the space areas corresponding to the respective pixels has been solved.
The above prior art examples are such that light-screening partitions (black matrices) are formed with a material different in critical surface tension from materials (inks) for a color filter, and the inks are applied to space areas between the partitions.
However, the materials described in these examples involve a problem in the following respects.
In the case of black matrices formed of a resin composition mainly containing a photosensitive resin, a non photosensitive resin, a black color-imparting material and an ink repellent (water repellent), the resin components and ink repellent in the resin composition, from which the black matrices are formed, are evaporated upon post-baking, which is a final step for forming the desired black matrix pattern, to thinly attach to the surface of a substrate. Therefore, the surface of the substrate also comes to exhibit an ink repellency, and inks applied to the substrate are hence difficult to adhere thereto and do not fully spread over the portions of the substrate surface corresponding to the space areas between the black matrices, resulting in a color filter which has blank areas (white portions) or irregularities or shows a tendency for the colored portions to separate from the substrate.